The invention concerns a traction device for vehicles having at least one ground engaging tire. In particular, the invention is directed to an emergency traction device that is readily fitted to tires of various diameters and widths. Additionally, the present invention is directed to an enhanced emergency traction device that substantially circumscribes a tire.
Known traction devices include snow tires, studded tires, and tire chains. The use of snow or studded tires requires that the vehicle operator anticipate the occurrence of inclement weather and replace the ordinary tires with the snow or studded tires. Consequently, two sets of tires are required which must either be alternately mounted on one set of vehicle wheels, or a second set of wheels must be obtained. Disadvantages of snow or studded tires include the cost of changing multiple set of wheels and/or tires, and the inability to react to unexpected weather.
Tire chains are commonly installed on the ordinary tires of a vehicle to enable an operator to react to, rather than anticipate, inclement whether. The disadvantages of tire chains include the need to have a set of chains sized to fit the particular tires of a vehicle, and the possibility of a chain being xe2x80x9cthrown-offxe2x80x9d a rotating wheel damaging the vehicle body.
Further, tire chains are generally installed by driving a tire onto the chain and subsequently linking the chain around the circumference of the tire. In the event the vehicle is already stuck, i.e. the tire spins without gaining traction, it is not possible to install the chains which could free the vehicle without elevating the tire off the ground.
U.S. Pat. No. 5,735,980 to Robeson discloses an emergency traction device in which the mechanisms for fitting the device to the diameter and width of the wheel each include a separate winch.
Other types of device intended to be attached to the tires and/or wheels of vehicles for the purpose of improving traction are described in the United States Patents to Laub U.S. Pat. No. 5,513,684, Metraux U.S. Pat. No. 5,254,187, Zelent U.S. Pat. No. 4,974,653, Parker, III U.S. Pat. No. 4,886,100, McDonough U.S. Pat. No. 4,862,936, Regensburger U.S. Pat. No. 4,209,049, Hyggen U.S. Pat. No. 4,122,880 and U.S. Pat. No. 3,891,018, Welsh U.S. Pat. No. 4,098,314, Gomez U.S. Pat. No. 3,847,196, Clark U.S. Pat. No. 3,736,970, Scott U.S. Pat. No. 3,249,143, Bopst III U.S. Pat. No. 3,053,302, Hayes U.S. Pat. No. 2,981,303, Binegar U.S. Pat. No. 2,910,105, Schroen U.S. Pat. No. 2,640,522, Pindjak U.S. Pat. No. 2,598,298, and Edwards U.S. Pat. No. 2,423,759. In general, these patents disclose traction devices having a plurality of arms extending outward toward the tread surface of the tire.
An object of the present invention is to provide an emergency traction device for attachment to a vehicle tire that is conveniently stored, easily adapted to tires of different diameters and widths, and is uniformly and securely installed.
Another object of the present invention is to provide an emergency traction device that may be readily installed and removed under any circumstances and terrain conditions.
Yet another object of the present invention is to provide an emergency traction device which is immediately transferable between alternate vehicles having different size tires.
A further object of the present invention is to provide an emergency traction device in which a single mechanism is used for fitting the device first to the diameter and then to the width of the wheel.
Yet a further object of the present invention is to provide an emergency traction device including additional traction devices overlying portions of the tread around a majority of a tire""s circumference.
These objects, as well as additional objects and advantages of the present invention that will be apparent from the following description, are achieved according to a traction device for attachment with respect to a tire rotating on an axis, wherein the tire has a terrain engaging surface connecting a pair of sidewalls. The traction device comprises a plurality of arms adapted to extend radially with respect to the axis, each of the plurality of arms including a first section adapted to be radially extensible with respect the terrain engaging surface and a second section adapted to be extensible across the terrain engaging surface, each of the plurality of second sections being mounted at a radially outward end of a corresponding one of the plurality of first sections; a plurality of fingers adapted to engage one of the pair of sidewalls, each of the plurality of second sections extensibly connecting a corresponding one of the plurality of first sections and a corresponding one of the plurality of fingers; a winch including a cable drum and a plurality of cables, each of the plurality of cables extending from a corresponding one of the plurality of fingers, along corresponding ones of the first and second sections, to the cable drum; a plurality of first springs each expanding a corresponding one of the first sections; and a plurality of second springs each expanding a corresponding one of the second sections. Each of the first springs has a lower spring constant than a corresponding one of the plurality of second springs.